105 lines
3.4 KiB
Plaintext
105 lines
3.4 KiB
Plaintext
README
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======
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This README file discusses the port of NuttX to the Raspberry Pi Zero.
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The Raspberry Pi Zero is based on the Broadcom BCM2835 CPU. This is the
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same Broadcom chip used in the Raspberry Pi Model A, B, B+, the Compute
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Module.
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STATUS
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======
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2017-10-09: This is a work in progress. The port is not complete and
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will not build to completion. Missing logic includes:
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- GPIO support,
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- System timer initialization, and
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- Serial driver.
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2017-10-19: Much of that logic is in place but there are a few things
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still missing.
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- Mini-UART Baud divisor calculation,
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- Start-up logic. My understand from what I have read on the internet
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is the PiZero OS starts up in hypervisor mode with the MMU and I- and
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D-Caches enabled. This probaby means that the standard, classic ARM
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startup logic at at arch/arm/src/arm/up_head.S will need to be replaced
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with some custom logic.
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No testing has yet been performed.
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Basic Setup
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===========
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+------------+
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| |
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| +--+
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| USB | | <----------------------------> USB Power Source
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| +--+ +------------+
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| | | +--+
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| +--+ | | | <---> Keyboard
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| USB | | <-------->| USB +--+
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| +--+ | HUB |
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| | | +--+
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| | | | | <---> Mouse
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| | | +--+
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| | +------------+
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| Mini +--+
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| HDMI | | <----------------------------> Monitor/TV
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| +--+
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+------------+
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You might be able to use the hub to power the Pi Zero, but I was not
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able to do that; my hub would not switch on power until it was enumerated
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by the host (the Raspberry Pi Zero), but then I could not power the Pi
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with the hub because it was not providing power. Chicken'n'Egg.
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NuttX Boot Sequence
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===================
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To be provided.
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Configurations
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==============
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Information Common to All Configurations
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----------------------------------------
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Each Raspberry Pi Zero configuration is maintained in a sub-directory
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and can be selected as follow:
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tools/configure.sh [OPTIONS] pizero/<subdir>
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Where [OPTIONS] include -l to configure for a Linux host platform and
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-c means to configure for a Windows Cygwin host platform. -h will give
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you the list of all options.
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Before building, make sure the PATH environment variable includes the
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correct path to the directory than holds your toolchain binaries.
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And then build NuttX by simply typing the following. At the conclusion of
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the make, the nuttx binary will reside in an ELF file called, simply, nuttx.
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make
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The <subdir> that is provided above as an argument to the tools/configure.sh
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must be is one of the following.
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NOTES:
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1. These configurations use the mconf-based configuration tool. To
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change any of these configurations using that tool, you should:
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a. Build and install the kconfig-mconf tool. See nuttx/README.txt
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see additional README.txt files in the NuttX tools repository.
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b. Execute 'make menuconfig' in nuttx/ in order to start the
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reconfiguration process.
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Configuration Sub-directories
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-----------------------------
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nsh:
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This simple configuration directory provide the NuttShell (NSH).
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